Numerous golf balls having two or more cover layers formed over the core, with the outermost layer made of a polyurethane-based elastomer or other resin material composed primarily of polyurethane, are available today on the market as golf balls for professional golfers and skilled amateurs. Moreover, much art has been described that attempts to, for example, increase the distance traveled by multi-piece solid golf balls having three or more pieces by optimizing the design (hardnesses, thicknesses, etc.) of the ball structure and forming the outermost layer of a urethane material.
For example, JP No. 3861983 describes a multi-piece solid golf ball of three or more pieces wherein the resin material in the outermost layer is formed of polyurethane, and parameters such as the thickness of the intermediate layer are controlled. JP-A 2003-190330 is a golf ball with an inner/outer two-layer cover in which a polyurethane elastomer is used as the primary material in the outer cover layer and the Shore D hardnesses of the core surface and the inner and outer cover layers are controlled. Also, JP No. 3661812 describes a golf ball which has an inner/outer two-layer cover, wherein the inner layer is hard and the outer layer is soft.
However, these golf balls all have a somewhat hard feel on shots with a driver (W#1) or are unable to increase the distance to an adequate degree for mid-level amateur golfers and low head-speed golfers. Hence, the) cannot be regarded as golf balls that are fully satisfactory in terms of having both a good, soft feel at impact and achieving an increased distance on full shots.